The invention relates to a belt-conveying installation for heavy industry and a method for operating such a belt-conveying installation.
Known belt-conveying installations may have at least one support structure, a conveying belt and at least one drive apparatus for driving the conveying belt. The drive apparatus in this case might include at least one drive shaft, at least one drive shaft bearing arrangement, at least one drive roller and at least one independently excited drive motor in the form of an alternating current synchronous motor which is fed by a frequency converter and has a stator and a rotor, wherein the drive shaft and the at least one drive motor are connected to one another without any gearing and wherein rotor and drive shaft are arranged coaxially. Such a belt-conveying installation is already installed at the Prosper-Haniel underground mine in Bottrop, Germany, for example, for the purpose of transporting extracted coal to the surface. A detailed description of this belt-conveying installation is disclosed in the company brochure entitled “Advanced Drive System Saves Up to 20% Energy” and published by Siemens Aktiengesellschaft (Order No. A19199-E273-B198-X-7600). The belt-conveying installation has two drive motors with a nominal power of more than 3000 kW each. The drive shaft for the conveying belt has at its end face a plurality of pegs, which are oriented parallel to the longitudinal axis of the drive shaft and onto which the rotor of the drive motor is laterally mounted.
A so-called direct drive is used here, no components being provided between drive motor(s) and drive shaft for the purpose of converting the rotational speed of the rotor into a different rotational speed of the drive shaft. The drive shaft therefore rotates at the same rotational speed as predetermined by the rotor or rotors. Both the drive shaft and the stator of the drive motor are arranged on a stable support structure in order to ensure that the gap dimension required for correct motor operation is maintained between rotor and stator. In such an application, the gap dimension between rotor and stator usually has a value of 5 to 15 mm. In order to ensure correct motor operation, an acceptable displacement between rotor and stator is usually in the range of 10 to 15% of the gap dimension.
The rotor used in this context due to the necessarily high nominal power of the drive motor weighs several tons, and therefore the bearings required for the drive shaft are so configured as to be correspondingly stable and the pegs on the end face of the drive shaft are subjected to an enormous load. Any change in the physical position of the belt-conveying installation in a mining operation therefore presents problems because the gap dimension must be reliably maintained at all times.